PROJECT SUMMARY We seek to establish an interdisciplinary training program at the Fred Hutchinson Cancer Research Center (Fred Hutch) focused on Infectious Diseases in the Immunocompromised Host. The purpose of the program is to train physician-scientists and post-doctoral PhD scientists to perform basic, translational and clinical research in the biology, pathogenesis, diagnosis, treatment and prevention of infectious diseases in high-risk immunocompromised patients. Novel drugs and biological agents to treat autoimmune diseases, advances in transplantation techniques and cancer treatments as well as increased survival of these patients have resulted in a significant growth in the population of patients with immunosuppression in the United States. Infection remains a major cause of morbidity and mortality for immunocompromised hosts, and with millions at risk or affected by emerging and established pathogens, there is increasing demand for research training in this field. The Infectious Disease Sciences Program of the Fred Hutch has partnered with the University of Washington in training 50 Infectious Disease fellows and postdoctoral scientists in laboratory or translational research in the area of Infectious Diseases in the immunocompromised host over the last 25 years. We have an excellent track record of transitioning trainees to full career independence at the conclusion of their training with more than 80% of our trainees now working in academia, government research or industry leadership positions. There is a clear need to both expand our training program and solidify funding for trainees in this specialized area of Infectious Diseases. We are requesting funding to support two qualified trainees (MDs and/or PhDs) per year, for two years of training for each of the trainees. This funding will be utilized for training in one of 4 research tracks that represent the unique strengths of our immunocompromised host program and its mentors: 1) Epidemiology, Pathogen Dynamics, and Clinical Trials; 2) Immunology/Immunogenetics; 3) Microbiome and Pathogenesis; and 4) Infection Prevention and Hospital Epidemiology. These tracks provide training in unique aspects of this field and will assure that trainees develop expertise in epidemiology, diagnosis, management and host-pathogen interactions. All trainees will participate in a rigorous core curriculum consisting of courses, lectures, retreats, research, and targeted career development activities; trainees also have the opportunity to complete a Masters in Public Health degree at the University of Washington. The proposed training program will help to address the national need for researchers that focus their clinical and/or laboratory investigation on Infectious Diseases in the Immunocompromised Host, and will provide those trainees with the skills and expertise to successfully transition into independent research careers.